This invention relates to kinetic propulsion and energy conversion.
Physics of Force. This invention is based on a branch of physics known as classical mechanics. Classical mechanics deals with the natural laws of motion, and is often associated with the ground-breaking work of Sir Isaac Newton. Newton, working in the late 17th and early 18th Centuries, realized that for every force exerted on a body, there is an equal but opposite reactive force. Imagine someone who pushes a shopping cart while standing on roller skates. Experience tells us that the cart will move forward and the person pushing the cart will tend to roll backward in the opposite direction. This is an everyday example of the principle that every action has an equal and opposite reaction.
This principle is the basis for all manner of propulsion, including walking, jet travel and rocketry. For example, a rocket propels itself through space by expelling matter in the form of burning propellant. The expulsion of matter through the tail of the rocket creates an equal but opposite force (or xe2x80x9cthrustxe2x80x9d) that propels the rocket forward in the desired direction. A more common illustration is the toy balloon that is inflated and released. The balloon will careen about the room as the air inside is expelled through the nipple. The air acts as a propellant, just like the fuel in a rocket.
The principle is equally applicable to terrestrial vehicles. In a motorboat, the turning propeller forces water toward the boat""s stern, propelling the boat forward. In a jet plane, the jet engine forces air and fuel toward the rear of the plane, creating thrust that moves the plane forward. In a car, the motive force is applied by the friction of a spinning tire on the road surface.
For each mode of transportation, the force or thrust pushing the vehicle forward is the result of an action-reaction force interchange (e.g., propeller against water). Key to this process is the existence of some external mass (such as water, air, road surface or discharging rocket fuel) against which the vehicle may impart a force. As Newton tells us, this force pushes the external mass in one direction, and the vehicle in the opposite direction, thereby propelling the vehicle as desired.
The energy of a moving vehicle such as a car, jet or bicyclist is called xe2x80x9ckineticxe2x80x9d energy. Vehicles use on-board engines (such as automobile motors, jet engines, and even the human body) to convert the xe2x80x9cpotentialxe2x80x9d energy in fuel (such as gasoline or food) into kinetic energy. Specifically, the consumption of fuel is used to move the engine (often in a rotating direction). The movement of the engine is converted into movement of the vehicle via a prop (in the case of a boat or plane) or drive transmission (in the case of a land vehicle).
Terrestrial Propulsion Problems. On Earth, there is usually no shortage of external mass (such as water, air, or ground) against which a vehicle or other object may be propelled. Nevertheless, there are situations where there is no convenient external mass to provide propulsion. For example, the tip of a very tall tower tends to vibrate and sway (or xe2x80x9coscillatexe2x80x9d) in an undesirable manner because there is nothing but air to anchor the tip of the tower. The tower tip is in effect a moving body (like a vehicle), whose motion we are interested in stopping. We would like to provide propulsive force in the opposite direction of the tower""s movement to stabilize the tower. Conceivably, one could place propellers on opposite sides of the tower, and use the thrust generated by the propeller to stabilize the swaying tower. However, this solution would be expensive, energy-consumptive, and otherwise wholly impractical.
Towers are usually stabilized by using guy wires to anchor the tower tip to the ground. This solution often limits the height of the tower, and, in the case of large towers such as office buildings is not practical or aesthetically acceptable. When guy lines cannot be used, the tower must be built with sufficient strength and rigidity to avoid swaying under normal loads (such as high winds). Unfortunately, earthquakes and other events may impose extraordinary loads on the tower, causing dangerous oscillation and eventually structural failure. Ideally, there would be a practical way of dampening oscillation by applying a motive force to the tower tip in the opposite direction of oscillation.
Extraterrestrial Propulsion Problems. Vehicles in space exhibit three broad classes of motion: oscillatory, rotational and linear. Oscillatory motion is a back and forth or vibratory motion such experienced by large flexible spacecraft undergoing attitudinal correction. Rotational motion is the spinning movement of a body, such as a space station or satellite rotating about its central axis. Linear motion is the straight-line movement of an object traversing between two points in space, such as a rocket accelerating away from the Earth and toward the moon.
Unlike our environment here on Earth, outer space is a vacuumxe2x80x94that is, a place devoid of any mass against which a body could propel itself. For example, an astronaut on a space walk would be unable to move relative to his or her ship if the tether connecting the astronaut were severed. Even with arms flailing and legs kicking, the astronaut could not propel him or herself back to the ship, or even so much as control the direction which he or she was facing. It is impossible to xe2x80x9cswimxe2x80x9d through space as one does through water because there is no mass in space against which to propel oneself.
Because space is a vacuum, a vehicle that will move through space in a controlled manner must bring along its own external mass in the form of propellant which is discharged to provide moving thrust. The difficulty is, propellant is quickly exhausted, leaving the vehicle adrift without any motive power. This makes space travel over long distances extremely difficult.
For example, a rocket traveling to the moon must bring many tons of propellant to both accelerate away from earth and decelerate upon arriving at the moon. Without propellant, the rocket is like the helpless, drifting astronaut discussed above. If there were a way for rockets to propel themselves through space without having to discharge propellant, it would greatly reduce the cost and difficulty of space travel.
Likewise, a satellite orbiting the earth must use tiny retro rockets to change the direction it faces or the manner in which it rotates. When the satellite exhausts its supply of fuel, its orientation can no longer be controlled. When this happens, the satellite is often permanently inoperable. Because millions of dollars are invested in building and launching the sat elites, it would be very valuable if satellite life could be prolonged by developing a way to maneuver the satellite without expelling physical propellant.
A similar situation will arise with proposed space stations. For many years, scientists have theorized that a large space station could be built and placed into orbit around the Earth. To simulate earth""s gravity for the benefit of the station""s occupants, the station would be rotated about a central axis. The centrifugal force experienced by someone at the peripheral of the rotating station would feel like gravity. The difficulty is, the only known way to set a large body such as a space station into spinning motion about its own axis is by placing retrorockets about the station""s perimeter, and directing the rockets"" thrust in a direction tangential to the desired arc of rotation. Depending on the weight of the station, this process would consume an exorbitant amount of propellant. Ideally there would be a way to spin a space station without using propellant. Although the cost per pound of payload is expected to go down, it is currently at $5,000 to $10,000. Thus, any technique for reducing the amount of propellant required would provide significant savings.
The sheer size of a space station raises other issues akin to the problem of anchoring a tall tower on earth. The station would likely be constructed using long, thin beams on the order of several hundred yards in length. These beams will be prone to vibration (much like the swaying of a tall tower on earth), which could become severe enough to cause structural failure.
Ideally, there would be a way of dampening the movement of vibrating space station beams. Unfortunately, just as the air on earth cannot practically be used to dampen the movement of a swaying tower tip, space offers nothing to xe2x80x9canchorxe2x80x9d the vibrating beams. Theoretically, the beams could be equipped with thousands of tiny retrorockets to exert propulsive forces to counteract beam vibration. This solution would be extremely expensive and would necessitate the use of propellant. What is required is a way of imposing a propulsive force on the beams without requiring the expulsion of propellant.
Existing Inertial Attitude Control Devices. It is in fact currently possible to control the rotation of satellites to some extent without having to expel propellant. In accordance with this technique, a flywheel on board the satellite is rotated or accelerated to change or correct the rotational momentum of the satellite. The difficulty with these existing techniques is that once the flywheel is rotated or accelerated, it cannot be returned to its original orientation or speed without offsetting the first change or correction. Thus, existing devices are of limited use.
The present invention is a technique for providing a propulsive force to a dynamic body without having to interact with an external mass. This technique is based on an internal exchange of kinetic energy working in concert with the influence of an ancillary force such as gravity to produce a net momentum change in the body. Using the invention, a body may be rotated or propelled through space without having to expel propellant or otherwise resort to an interaction with an external mass. The invention can also be used to dampen a swaying motion or vibration of a body (such as a tall earth-bound tower or a beam in a space station) when there is no convenient external mass to which the body may be anchored.
In one embodiment, the invention provides propulsion in an oscillating system such as a swaying tower, vibrating member of a space station, or a simple swinging pendulum.
In the case of the simple swinging pendulum, the system includes a chamber suspended for oscillation by a tether. Inside the chamber is a ball mass, two spaced-apart solenoids that can be fired on command, and an electric energy source for controlling the solenoids. The solenoids are fixed on the left and right side of the chamber so that each can fire the ball mass toward the other, much like two people playing catch.
Initially, the pendulum system is stationary, with the ball mass resting on the left solenoid. To begin oscillation, the left solenoid launches the ball mass toward the right solenoid. As the ball mass is launched from the left solenoid, a reactive exchange of forces occurs, pushing the ball to the right and the solenoid to the left. Because the solenoid is fixed to the chamber, the result of this force is to swing the whole chamber to the left. The effect is much like a child xe2x80x9cpumpingxe2x80x9d a swing. In physical terms, the movement of the system is caused by shifting the center of gravity.
The pendulum chamber moves leftward and upward until its motion is overcome by the downward force of gravity, which eventually pulls the chamber back rightward toward its initial starting position. As the chamber moves through this half-cycle of oscillation, the ball mass travels as a free body until it collides with the right solenoid.
This initial movement can be thought of as a xe2x80x9cseed pulse.xe2x80x9d One can build momentum onto this seed pulse by further shuttling the ball mass between the left and right solenoids in accordance with the invention.
For example, after the seed pulse, the ball mass will be resting in the right solenoid with the chamber swinging rightward towards its rightmost zenith. To build on the momentum of the seed pulse, the ball mass is launched from the right solenoid just before the chamber reaches its rightmost zenith. The launch of the ball from the right solenoid imposes an action-reaction force interchange that pushes the chamber above the rightmost zenith that it otherwise would have attained.
The speed and trajectory of the ball launch are selected so that the ball mass collides with the left solenoid after the rightmost zenith has been crossed and while the chamber is swinging leftward towards its leftmost zenith. Thus, the second collision with the left solenoid results in a reactive exchange of force wherein the ball mass is brought to rest and the left solenoid (and, as a direct consequence, the entire chamber) is pushed leftward.
Both the launch of the ball from the right solenoid and the collision of the ball with the left solenoid contribute constructively to the momentum of the system. The process can be repeated left-to-right and right-to-left to build the oscillation.
To decelerate the oscillation, a xe2x80x9csoft-landingxe2x80x9d slowdown sequence is used, whereby the ball mass is shuttled between the solenoids in a manner that dampens the momentum of the swinging pendulum. This slowdown sequence begins just after the chamber has passed its leftmost zenith, and is accelerating rightward. (Starting the slowdown sequence at the left zenith is an arbitrary choice; the sequence could just as easily begin at the right zenith). At that point, the ball mass is launched from the left solenoid toward the right solenoid. As the ball mass is launched from the left solenoid, a reactive exchange of forces occurs, imposing a rightward impulse on the ball mass and a leftward impulse on the chamber. A vectored component of this leftward impulse is in the opposite direction as the chamber""s rightward acceleration, and therefore cancels some of the chamber""s rightward velocity.
The chamber continues accelerating rightward (under the force of gravity). As the chamber accelerates, the ball mass, now a free floating body, moves toward and eventually collides with the right solenoid. By carefully choosing the speed and trajectory of the ball mass"" launch, the collision between the ball mass and the right solenoid occurs at a point in time when the chamber""s velocity has just matched that of the right solenoid. Because the velocities of the ball mass and chamber are exactly or substantially equal, their collision results in a virtually reactionless exchange. Consequently, no momentum is transferred to the chamber as a result of the ball""s landing on the right solenoid.
The net effect of shuttling the ball mass between the solenoids is to impart an impulse of force which decelerates the swinging pendulum. When the chamber passes its rightmost zenith, the ball mass can be fired from the right solenoid toward the left solenoid in the same manner as described above. The process can be repeated until the pendulum""s motion has been diminished to a desired level.
A xe2x80x9chard-landingxe2x80x9d slowdown sequence may also be used to decelerate oscillation. The hard-landing slowdown sequence begins after the chamber has reached its leftmost zenith, and is accelerating and moving rightward under the force of gravity. As the chamber passes the xe2x80x9cat restxe2x80x9d position of the chamber system, it attains its maximum velocity. Shortly after this point, the ball mass is launched by the left solenoid toward the right solenoid. As the ball mass is launched from the left solenoid, a reactive exchange of forces occurs, pushing the ball to the right and imposing a leftward impulse on the chamber. A vectored component of this leftward impulse is in the opposite direction as the chamber""s rightward velocity and therefore cancels some of that velocity.
The chamber continues moving rightward but decelerating under the force of gravity. Eventually the chamber reaches its rightmost zenith and begins accelerating back leftward under the force of gravity. During this period, the ball mass has been moving rightward as a free floating body toward the right actuator. The ball mass then collides hard with the right solenoid, which is moving in the opposite direction as the ball mass. This hard collision results in an action-reaction exchange wherein the momentum of the ball is transferred to the chamber, imposing a rightward impulse on the chamber that cancels a portion of the chamber""s leftward velocity.
Unlike the soft-landing sequence, the hard-landing sequence can be used to bring the chamber to a halt. Like the soft-landing sequence, the hard-landing sequence requires judicious timing so that the ball mass collides with the right (left) actuator after the rightmost (leftmost) zenith of a pendulum system has been obtained. This same hard-landing slowdown process can be used to stabilize the swaying tip of a tall tower or a vibrating member of a space station, as explained below.
In another embodiment, the invention provides rotational propulsion to a rotating system. This embodiment is useful, for example, in adjusting the rotation of a satellite or in rotating a massive space station. In accordance with this embodiment a rotating system or xe2x80x9cdriverxe2x80x9d is attached to the satellite, space station or other primary mass in space which is to be rotated. The driver includes two rigid arms extending radially from opposite sides of the driver. At the distal end of each arm is a chamber much like the chamber described above in connection with the pendulum system. Each distal arm is capable of telescopic-like extension and contraction.
The rotational propulsion begins by coupling the driver to the primary mass and rotating the drive relative to the primary mass using a conventional electromechanical source fixed to the primary mass. As the motor rotates the driver, it causes reactive interaction between the driver and the primary mass, thus imposing a rotational impulse on the primary mass in the opposite direction as the rotation of the driver.
Once the driver has reached a predetermined rotational velocity, it is disengaged from the primary mass leaving both the driver and the primary mass free-wheeling in opposite directions. At this point, the driver may be decelerated in accordance with the invention without expelling propellant or imparting an impulse to the primary mass that offsets the first impulse. Once the driver has been decelerated, it can be recoupled to the primary mass and then reaccelerated using the electromagnetic motor to apply a second rotational impulse to the primary mass. As this process is repeated, the impulses applied to the primary mass build, resulting in substantial rotational acceleration of the primary mass.
The deceleration of the driver is accomplished in accordance with the invention as follows. During each half-revolution of the driver, the radially extending arms each execute a contraction and extension cycle, whereby the spinning chambers are drawn in toward the driver and then meted out away from the driver. Since the driver is in a free-wheeling rotation, its rotation is accelerated when the chambers are drawn in, and decelerated when the chambers are let out.
The chambers connected to the distal end of each arm are comparable in construction to the chamber used with the pendulum system described above, and accordingly include two solenoids and a ball mass shuttled between the solenoids. At the beginning of each half-revolution, the ball mass in each chamber is launched from one actuator to the other so that the ball mass is moving in generally the same direction as the chamber. These launchings impart a reactive force against each chamber in the opposite direction as its rotation, which has the effect of decelerating the driver.
Upon launching, each ball mass coasts through space as a free body toward the opposing solenoid. An instant after the ball mass is launched, the radial arms each contract, drawing their respective chambers closer to the driver, and increasing each chamber""s tangential velocity as it rotates about the driver-until the velocity of the chamber is equal or close to the velocity of the ball mass.
Through careful launch timing, each chamber reaches this velocity at the same time that its respective ball mass collides with the opposing solenoid. Because the velocity of the ball mass and the opposing solenoid are identical (or at least close) at impact, the collision is reactionless (or nearly so), and does not significantly change the angular momentum of the driver. The effect of shuttling the ball mass from one solenoid to another is a net momentum change that slows down the driver. This process can be repeated every half-rotation of the driver until its angular momentum has been substantially reduced.